CD36 expression in the brains of SAMP8.

SAMP8, senescence accelerated mice with age-related deficits in memory and learning, are known to show age-related increases of amyloid precursor protein (APP) and immunopositivity for amyloid-β (Aβ) proteins, and moreover to be under elevated oxidative stress. The elevated expression of class B scavenger receptor CD36, which is the receptor of oxidized LDL and also one of efflux transporters of Aβ proteins in the cerebral vessels, is thought to mediate free radical production in cerebral ischemia and induce oxidative stress. Accordingly, by real-time quantitative reverse transcriptase-polymerase chain reaction (RT-PCR), Western blotting, and immunohistochemical techniques, we examined whether the expression of CD36 was increased in the brains of 10-12-week-old SAMP8 with elevated oxidative stress. Ten to 12-week-old SAMR1 mice were used as controls without the features. The gene and protein expression of CD36 was significantly higher in the brains of SAMP8 than those of SAMR1. Confocal microscopic examination revealed that the CD36 immunoreactivity was seen in the cytoplasm of endothelial cells and F4/80-positive perivascular cells of the brains. These findings indicate that the expression of CD36 in the brains of SAMP8 is increased compared with that of SAMR1.